1. Field of the Invention
The present invention relates to a head support mechanism provided in a magnetic disk apparatus for use in a computer storage apparatus and the like. More particularly, the present invention relates to an optimal head support mechanism for high-density data recording, and a thin film piezoelectric actuator suitable for the head support mechanism.
2. Description of the Related Art
Recently, the recording density of a magnetic disk provided in a magnetic disk apparatus has been vigorously increased. A magnetic head for use in recording and reproducing data to and from a magnetic disk is typically provided on a slider. The slider carrying the magnetic head is supported on a head support mechanism provided in a magnetic disk apparatus. The head support mechanism has a head actuator arm to which the slider is attached. The head actuator arm is rotated by a voice coil motor (VCM). The head provided on the slider is placed at an arbitrary position on a magnetic disk by controlling the voice coil motor.
High-density data recording on a magnetic disk requires a high level of precise positioning of the magnetic head. In the case where the positioning of the magnetic head is performed by the VCM rotating the head actuator arm, there is a problem in that the positioning of the magnetic head is less precise. To avoid such a problem, a head support mechanism has already been proposed which achieves high-precision positioning of the magnetic head.
FIG. 45 is a top view illustrating a conventional head support mechanism 400 for use in a magnetic disk apparatus. A head 402 is used to record and reproduce data to and from a rotating magnetic disk (not shown). The head 402 is supported on an end portion of a suspension arm 404. The other end portion of the suspension arm 404 is supported on a projection portion 408 provided in the tip portion of a carriage 406 in such a manner as to rotate within a small angle range on the projection portion 408. A base portion of the carriage 406 is supported on an axis member 410 fixed to a housing of the magnetic disk apparatus in such a manner as to rotate on the axis member 410.
A permanent magnet (not shown) is fixed to the carriage 406. A drive coil 414 as a part of a magnetic circuit 412 fixed to the housing is controlled by an excitation current flowing therethrough. The carriage 406 is rotated on the axis member 410 by interaction of the permanent magnet and the drive coil 414. Thereby, the head 402 is moved in a substantially radial direction of a magnetic disk.
A pair of piezoelectric elements 416 are provided between the carriage 406 and the suspension arm 404. The longitudinal directions of the piezoelectric elements 416 are slightly deviated from the longitudinal direction of the carriage 406 in opposite directions. The suspension arm 404 is rotated within a small angular range on the projection portion 408 and along a surface of the carriage 406 by expansion or contraction along a direction indicated by arrow A14 of the piezoelectric elements 416. Thereby, the head 402 attached to the tip portion of the suspension arm 404 is moved along a surface of a magnetic disk within a small range so that the head 402 can be precisely placed at a desired position on the magnetic disk.
In the conventional head support mechanism 400 of FIG. 45, each piezoelectric element 416 is interposed between the suspension arm 404 and the carriage 406. Side portions in the longitudinal direction of each piezoelectric element 416 contact the suspension arm 404 and the carriage 406. Deformation of each piezoelectric element 416 causes the suspension arm 404 to be rotated so that the head 402 is slightly displaced. In other words, a voltage is applied to each piezoelectric element 416 to cause the rotation of the suspension arm 404, resulting in a small displacement of the head 402. However, the head 402 does not always follow the voltage applied to each piezoelectric element 416 with great precision. It is thus unlikely that the head 402 is precisely placed at a desired position.
According to one aspect of the present invention, a head support mechanism includes: a slider for carrying a head at least for performing reproduction of data from a disk; and a holding portion for holding the slider. The holding portion includes: a first portion including a first piezoelectric element; a second portion including a second piezoelectric element; a third portion connected to the first and second portions, the slider being provided on the third portion; and a fixing portion for fixing the first and second portions. At least one of the first and second piezoelectric elements is contracted and expanded in a direction substantially parallel to a surface of the disk, in the presence of an applied voltage so that the slider provided on the third portion is rotated around a predetermined center of rotation.
In one embodiment of this invention, the head support mechanism further includes a load beam provided at a side of the holding portion opposite to the slider. The load beam includes a dimple projecting toward the slider in such a manner as to apply a load to the slider. The holding portion further includes a first joining portion for joining the first and third portions, and a second joining portion for joining the second and third portions. The dimple is provided at a substantially middle point between the first and second joining portions.
In one embodiment of this invention, the first and second joining portions include first and second elastic hinges, respectively, each having a width sufficient to reduce a load required for rotation of the slider.
In one embodiment of this invention, the first and second portions include first and second conductor patterns provided along the first and second elastic hinges, respectively. The first and second elastic hinges each have a minimum width required for providing the first and second conductor patterns, respectively.
In one embodiment of this invention, the head support mechanism further includes: a load beam provided at a side of the holding portion opposite to the slider; and a slider holding plate provided between the third portion included in the holding portion and the load beam. The load beam includes a dimple projecting toward the slider in such a manner as to press the third portion via the slider holding plate. The slider holding plate has such a shape that the center of gravity of a combination of the slider holding plate and the slider substantially corresponds to the predetermined center of rotation.
In one embodiment of this invention, the load beam includes a regulation portion for regulating the slider holding plate.
In one embodiment of this invention, the dimple contacts a point of the slider holding plate to support the slider holding plate pressing the third portion in such a manner that the third portion can be rotated in all directions including a pitch direction, a roll direction, and a yaw direction.
In one embodiment of this invention, the head support mechanism further includes: a load beam provided at a side of the holding portion opposite to the slider; and a slider holding plate provided between the third portion included in the holding portion and the load beam. The load beam includes a dimple projecting toward the slider in such a manner as to press the third portion via the slider holding plate. The slider provided on the third portion is rotated on the dimple acting as the predetermined center of rotation.
In one embodiment of this invention, the second portion is provided in such a manner that a distance between the second portion and the surface of the disk is substantially equal to a distance between the first portion and the surface of the disk.
In one embodiment of this invention, the first portion includes a first electrode for applying a voltage to the first piezoelectric element; and the second portion includes a second electrode for applying a voltage to the second piezoelectric element.
In one embodiment of this invention, the first portion includes a first substrate. The second portion includes a second substrate. The first and second substrates are provided along a tangential direction of the disk. At least one of the first and second piezoelectric elements is contracted and expanded in a direction substantially parallel to the surface of the disk in such a manner that at least one of the first and second substrates is bent in a direction nearing or leaving the disk, so that the slider carrying the head is rotated by a small amount in a yaw direction.
In one embodiment of this invention, at least one of the first and second piezoelectric elements is contracted and expanded in a direction substantially parallel to the surface of the disk in such a manner that only one of the first and second substrates is bent in a direction nearing or leaving the disk, so that the slider carrying the head is rotated by a small amount in a yaw direction.
In one embodiment of this invention, the first and second portions further include first and second flexible materials covering the first and second piezoelectric elements and the first and second substrate, respectively.
In one embodiment of this invention, the slider has an air bearing surface on which an appropriate air flow is generated between the slider and the rotating disk. The third portion is arranged so that a center position of the air bearing surface substantially corresponds to the predetermined center of rotation.
Accordingly to another aspect of the present invention, a head support mechanism includes: a slider for carrying a head at least for performing reproduction of data from a disk; and a holding portion for holding the slider. The holding portion includes: a first portion including a first piezoelectric element; a second portion including a second piezoelectric element; and a fixing portion for fixing the first and second portion. At least one of the first and second piezoelectric elements is contracted and expanded in a direction substantially parallel to a surface of the disk, in the presence of an applied voltage so that the slider is rotated around a predetermined center of rotation. The head support mechanism further includes: a load beam provided at a slide of the holding portion opposite to the slider; and a slider holding plate provided between the holding portion and the load beam and provided at a position corresponding to the slider. The load beam includes a dimple projecting toward the slider in such a manner as to press the third portion via the slider holding plate. The slider holding plate as such a shape that the center of gravity of a combination of the slider holding plate and the slider substantially corresponds to the predetermined center of rotation.
In one embodiment of this invention, the holding portion further includes a third portion, the slider being provided on the third portion. At least one of the first and second piezoelectric elements is contracted and expanded in a direction substantially parallel to the surface of the disk, in the presence of applied voltage so that the third portion is rotated around the predetermined center of rotation.
In one embodiment of this invention, the holding portion includes a first joining portion for joining the first and third portions, and a second joining portion for joining the second and third portions. The dimple is provided at a substantially middle point between the first and second joining portions.
In one embodiment of this invention, the slider is rotated on the dimple corresponding to tho predetermined center of rotation.
In one embodiment of this invention, the second portion is provided in such a manner that a distance between the second portion and the surface of the disk is substantially equal to a distance between the first portion and the surface of the disk.
According to still another aspect of the present invention, a method for producing a thin film piezoelectric element, includes the steps of: a) forming a first metal electrode film, a first thin film piezoelectric element, and a second metal electrode film on a first substrate in this order; b) forming a third metal electrode film, a second thin film piezoelectric element, and a fourth metal electrode film on a second substrate in this order; c) attaching the second metal electrode film to the fourth metal electrode film; d) removing the first substrate by etching; e) shaping the first metal electrode film, the first thin film piezoelectric element, the second metal electrode film, the fourth metal electrode film, the second thin film piezoelectric element, and the third metal electrode film; f) covering the first metal electrode film, the first thin film piezoelectric element, the second metal electrode film, the fourth metal electrode film, the second thin film piezoelectric element, and the third metal electrode film, with a coating resin; and g) removing the second substrate by etching.
In one embodiment of this invention, the first and second substrates are each a mono-crystal substrate.
In one embodiment of this invention, the linear expansion coefficient of the first substrate is greater than the linear expansion coefficient of the first thin film piezoelectric element. The linear expansion coefficient of the second substrate is greater than the linear expansion coefficient of the second thin film piezoelectric element.
In one embodiment of this invention, step c) includes attaching the second metal electrode film to the fourth metal electrode film using a conductive adhesive.
In one embodiment of this invention, step c) includes attaching the second metal electrode film to the fourth metal electrode film using a thermal melting technique using ultrasonic vibration.
In one embodiment of this invention, step a) includes forming the first thin film piezoelectric element in such a manner that a polarization direction of the first thin film piezoelectric element substantially corresponds to a direction perpendicular to a surface of the first thin film piezoelectric element. Step b) includes forming the second thin film piezoelectric element in such a manner that a polarization direction of the second thin film piezoelectric element substantially corresponds to a direction perpendicular to a surface of the second thin film piezoelectric element.
According to still another aspect of the present invention, a thin film piezoelectric device includes: a first metal electrode film; a first thin film piezoelectric element provided on the first metal electrode film; a second metal electrode film provided on the first thin film piezoelectric element; a third metal electrode film; a second thin film piezoelectric element provided on the third metal electrode film; a fourth metal electrode film provided on the second thin film piezoelectric element; and adhesive means for attaching the second metal electrode film to the fourth metal electrode film.
In one embodiment of thin invention, the thin film piezoelectric device further includes voltage applying means for applying a voltage to the thin film piezoelectric device. The voltage applying means includes: a first terminal for applying a driving voltage to the first and third metal electrode films, and a second terminal for grounding the second and fourth metal electrode films.
According to still another aspect of the present invention, a head support mechanism includes: a slider for carrying a head; and a holding portion for holding the slider. The holding portion includes: a first portion including a first piezoelectric element; a second portion including a second piezoelectric element; a third portion connected to the first and second portions, the slider being provided on the third portion; and a fixing portion for fixing the first and second portions. The first and second piezoelectric elements include the above-described thin film piezoelectric device.
Thus, the invention described herein makes possible the advantages of providing: (1) a head support mechanism for use in a disk apparatus, which enables a head to move by a small displacement with great precision for the purposes of tracking correction and the like for a magnetic disk and the like; (2) a head support mechanism for use in a disk apparatus, which enables a head to move by a small displacement with great precision by control of a voltage; and (3) a thin film piezoelectric actuator preferably used for such head support mechanisms.
These and other advantages of the present invention will become apparent to those skilled in the art upon reading and understanding the following detailed description with reference to the accompanying figures.